Process of making briquettes



Patented June26, 1928.

UNITED STATES PATENT OFFICE.

PROCESS OF MAKING BRIQUETTES.

No Drawing. Application filed July 28, 1922, Serial No. 578,262, and in Germany May 24, 1921.

This invention relates to a new or improved process for the production of huquettes from bituminous or carbonaceous and like materials, as for example, small coal, lignite, peat and the like.

Heretofore, briquetting processes may be said to have been divided into two prlnci al' classes. In one of these, there was ad ed to the material a binder medium of an entirely different nature, as for example, cement, plaster of Paris, and the like. In the other of these classes there was added to the material a binder having a composition similar to that of the material to be briquetted, or the binder medium was formed by special treatment of the bituminous substances in the raw material itself. For example, pitch, naphthalene, and the like have been added as binders, or binding mediums have been produced in the raw material itself as by means of the heat and pressure used in carrying out the briquetting process.

The process according to the present invention difiers essentially from those practi'sed heretofore, and is distinguished by effecting a change in the physical condition of the material to be briquetted and using this physically changed material as a binding medium. In this, the invention is distinguished from the known processes in which bituminous and like binders are added to the material, and from the known 'processes in which bituminous and like constituents of the raw material are influenced by pressure and heat conditions of the briquet- 4 ting process so that they function as binders.

According to this invention, a portion of the raw material to be briquetted, or a predetermined quantit of a similar material, is ground to colloi a1 fineness in water and is thoroughly mixed with a suitable 'amount of the raw material to be briquetted. It has been found that in the briquetting of such a mixture, only relatively low pressures are necessary for the product-ion of quite firm and hard briquettes. The portion ground to colloidal fineness as aforesaid, acts as a very efiicient binder and the briquettes pro duced with even relatively low pressure satisfy all technical requirements. The nature of the actions or reactions taking place durin the process can only be presumed but it is not at all improbable that the colloidal slimesof the very finely ground material are very diffusely distributed and fill up all interstices of the mass of material to be briquetted so that cohesion is increased to such a degree as to produce firm hard blocks as aforesaid.

It is not necessary for the purposes of this invention that the colloidally ground material should be the same as the raw material forming the principal constituent of the briquettes, as it may be advantageous to choose for the purpose such material as will give the best yield of colloidal medium and furnish the best results.

In addition to facilitating the production of firm hard blocks, the invention also presents a further advantage which will now be referred to. It has been found that materials which only dry with great difliculty when briquetted in the ordinary way will give up their water or moisture content within an essentially shorter period when briquetted in accordance with this invention. This is a quite unlocked for result and is especially striking when using peat for the manufacture of the briquettes. For example, raw peat is taken containing anything up to 90% of moisture and the moisture contact is reduced by suitable means, and without experiencing any techincal difliculty to -70% and if the raw material is t en briquetted with the addition of, say, 6% (calculated upon the basis of dry peat) of peat slime produced by grindingto colloidal fineness, the briquettes will lose so much moisture during the pressin operation and during a few days in stac s or heaps that the moisture content will be reduced to 20-25%. On the other hand, it is known .to be a fact that the same reduction of moisture in raw peat, when the latter is dried in the usual manner in the open air, requires several months. This is a surprising result which cannot be accounted for theoretically. As a further example, brown coal, wet from the pit, can be directly briquetted in a similar manner.

The new or improved process, therefore, possesses great simplicit and is very economical in view of the act that high pressures and high temperaturm are not required. Also, it possesses the advantage, in common with other processes involving the addition of organic binders, that no increase in the content of ashes is necessary owing to the addition of binder mediums of a different kind. Upon the nature of the material to be agglomerated, that is to say the degree of ease or difliculty with which it lends itself to agglomeration, depends the question whether or not other materials can be mixed with it for agglomeration. For

- example, in the case of raw materials which readily lend themselves to agglomeration or binding, it is possible to mix with them substances or materials which in themselves lessen or tend to lessen the agglomerative capacity of the mass. As an instance, a mass of peat to be agglomerated can have a higher percentage of coke waste or small coke added to it in admixture than heretofore. Also, brown coal or lignite can have added to it in admixture nuts or knobs of brown coal which have been previously separated from it by sifting or riddling, which nuts or knobs have heretofore presented difliculties in attempts to agglomerate or bind them in briquettes. It has been found that these admixtures, in many cases, facilitate the reduction of the moitsure content of the briquettes not solely on account of the smaller water content of the added materials but also on account of their influence on the internal structure of the block.

Briquettes produced in accordance with this process are suitable for all general heating urposes and also for the purposes of gasi cation and distillation, according to the materials employed for their composition.

In order to enable the invention to be more readily understood, the practical carrying out of one process will now be given by way of example.

Assume the raw material to consist of raw peat which is equalized or made uniform in known manner and contains 90% of moisture. As a first step, this moisture content may be readily reduced to 60% by the use of presses of known construction. A portion of this peat with reduced moisture content is now ground with water in suitable grinders to such a de ree of fineness that a completely even an smooth slime is obtained which, practically speaking, represents matter in permanent suspension. The mass of raw material to be agglomerated may now be composed so as to consist of 79 parts of peat and 15 parts of small coke or waste coke. To this mass of mixture is now added a quantity of the slime equal to about 6 parts calculated on the basis of the dry peat, and this slime is diffusely distributed in the mass so as to form an uniform mixture by the aid of any suitable mixing machine. The mass is now employed for the makin of briquettes in briquette resses and a slight heating of the moulds 0 these presses during the pressing may be beneficial. This heating may be done by exhaust steam from an englne.

Briquettes, made in accordance with the foregoing example, are delivered from the press containing approximately 35% of moisture and, if stored'in sheds in single layers, the percentage of moisture will be further reduced by evaporation to 20-25% within the space of 36 to 48 hours. Of course, this supplementary drying can be forced or hastened, provided that heated air is available, in the event of immediate shlpment of the briquettes being essential. With such supplementary or accelerated drying, the briquettes may be dried down to a moisture content of 2530% of moisture within a few hours.

Owing to the high content of oxygen in briquettes made in this way, particularly briquettes ,made of mixtures, they require little air for combustion, they ignite easily and give off gas uniformly and easily. By admixture of suitably chosen raw materials, briquettes can be obtained of graded calorific value, within possible limits.

It has already been mentioned that briquettes produced by the improved process may be very advantageously made use of for 00king purposes. In proportion, as the constituents themselves are capable of being coked, lump coke is obtained suitable for use in furnaces. However, in the case of raw materials which of themselves would not produce any concrete coke capable of withstandin pressure, no such coke could be produced y this process.

Nevertheless, it has been proved that the present process is exceedingly advantageous in combination with those known processes by means of which lump coke is obtained from raw materials which do not coke by themselves. For example, it has been suggested to add to brown coal such substances as will act as fluxes during coking, including boric acid, clay or earth silicates, alkali compounds and so on, in order to produce a certain degree of sintering. In practising the present invention it has been found that such sintering processes are carried out much more favourably that is to say with less addition of such materials as have been referred to, if the raw materials which are to be converted into lump coke are first briquetted in accordance with the process above described and if the fluxes are added to the colloidal slimebinding medium as well as such materials as are re uired to give off carbon during coking, suc as highly molecular tar oils, tar residues and the like. In such slimes to be employed as binding media, therefore, there would be contained for example, small quantities of boric acid and tar in fine distribution. By this means a firm smelting coke capable of withstanding pressure and suitable for smelting furnace work can be produced, for example, from brown coal, lignite, peat and the like.

I claim substantially permanent suspension in wa ter, the colloidalfuel being uniformly distributed throughout the said mass, and being in addition to any naturally occurring colloidal material in such fuel.

2. A process for briquetting coal, lignite,

peat and like materials which comprises grinding at least one of such materials in water to such a condition of fineness that originally-noncolloidal solid parts thereof assume the condition of a colloidal dispersion and substantially permanent suspension, and thereafter mixing a quantity of said so formed colloidal dispersion With a quantity of the carbonaceous material to be briquetted in such proportions as to enable it to be molded into briquettes.

3. The process for briquettin nous, carbonaceous and like materlals which comprises mixing with the material to be briquetted a binder including at least two binding materials of diflerent binding capaciti es ground to colloidal fineness, the ground particles of which being capable of remaining in substantially permanent suspension in water.

4. A process for briquetting coal, peat and like material which comprises mixing with the material to be briquetted a binder formed of at least one of said materials having its ground to colloidal fineness, the ground particles being capable of remaining in substantially permanent suspension in water.

PETER JUNG.

bitumioriginal non-colloidal parts 

